1. Field of the Invention
The present invention relates to an image processing apparatus and a control method thereof, and particularly to an image processing apparatus and an image processing method that handle RAW images.
2. Description of the Related Art
Conventionally, an imaging apparatus using a single-panel color image sensor generally applies the so-called development process to image information (RAW image) obtained by an image sensor, and performs compression encoding on the developed luminance signal and color difference signal, and records the encoded signals in a JPEG format in a recording medium. The development process includes, but is not limited to, a demosaicing for performing color interpolation on each pixel to generate a signal composed of a luminance and a color difference, noise reduction on the signal, white balancing, optical distortion correction, and image optimization.
Meanwhile, there are imaging apparatuses capable of recording RAW images (Japanese Patent Laid-Open No. 2011-244423). As compared with JPEG format or the like, a RAW image requires an enormous amount of data for recording, but is advantageous in that it allows flexible post editing, while minimizing deterioration in image quality.
Japanese Patent Laid-Open No. 2011-244423 describes a configuration in which the development and reproduction of a RAW image are performed by using development parameters record together with the RAW image.
In recent years, the data amount per image of imaging apparatuses has significantly increased owing to the use of imaging elements having a large number of pixels. The continuous shooting speed and the number of images that can be continuously shot also tend to increase. Consequently, the amount of various types of processing constituting a development process on RAW image, such as demosaicing, noise reduction, and optical distortion correction, has been increased along with such increases. Accordingly, a circuit for high-speed processing is required to apply the development process in real time in parallel with capturing, which has led to an increase in the circuit scale and the power consumption. In addition, in order to allocate the processing capability and the electric power to the development process, there may be restrictions on the capability (e.g., continuous shooting capability) of the imaging apparatus during the development process.
When a configuration in which a RAW image is recorded without being developed is adopted as described in Japanese Patent Laid-Open No. 2011-244423, whether the development process can be applied in real time would not be a problem. However, the amount of data recorded is increased, and it may thus be necessary to increase the buffer amount. In addition, the development process is necessary to check a result of capturing, and thus takes time. Moreover, the data format of the RAW image is unique to each manufacturer. Accordingly, an appropriate development process may not be able to be applied by an apparatus different from the imaging apparatus that has performed capturing, and there is the risk of impairing user convenience. This poses a problem especially during moving image capturing when a larger amount of data is handled.
As such, in order for high capturing capacity and high-speed reproduction of captured images to be achieved, it has been necessary to enable a high cost and high power consumption circuit having high processing capability to be installed and driven at high output, or to enable a recorded RAW image to be reproduced at high speed.
To solve such a problem, it is conceivable to, for example, record RAW image data and also to record moving image data in a general-purpose format (e.g., MPEG format) during moving image capturing by applying a development process that is simple enough to be performed at high speed without using a high-performance circuit. However, in this case, the quality of the moving image data in a general-purpose format is not high, and therefore, encoding noise, dark noise, and the like become noticeable, for example, when the moving image data is reproduced by slow reproduction.